JPH0547728B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a large number of ball rolling elements, and these rolling elements move in an infinite straight line on a track rail to handle vertical loads, lateral loads, moment loads, etc. Concerning linear motion guide units that perform linear motion with stable precision and high rigidity while receiving complex loads, narrow overflow types are used in various linear motion mechanisms that require high precision, such as machine tools that are subject to vibration and shock, and industrial robots. Regarding linear guide units.

[Prior art]

For example, a linear motion guide unit including ball rolling elements is disclosed in Japanese Patent Application No. 59-109573 (see Fig. 5) filed by the same applicant. It consists of a casing 2' that is movably placed and has a U-shaped cross section, and ball rolling raceway grooves are formed on both side surfaces of the rail-like member 1', and on the inner surface of the casing 2' there are grooves provided on the rail. raceway grooves corresponding to the raceway grooves are formed to form load tracks for the balls between the rail and the casing, and the casing is further formed with return holes 7' extending parallel to each of the load tracks; The casing has side plates fixed to both ends in the sliding direction,
Each of the side plates has a curved direction change path 5' that directly connects the load raceway groove on the casing side and the return hole.
A linear guide unit is disclosed in which each return hole formed in the casing is formed in the upper inward direction with respect to the position of the ball in the load track when viewed in cross section of the casing.

This new configuration brought great benefits, such as being able to reduce the width of the casing and allowing the unit to be used in narrow spaces that were previously unusable. There was a problem.

In other words, the length of the curved and extended direction changing path becomes longer than necessary, and conversely, the movement resistance of the ball increases.

The curved shape of the direction change path formed on the side plate becomes complicated, and the processing cost increases.

The number of balls that can enter the direction change path increases, which increases the cost of the entire unit.

(Refer to Figure 5) The return hole is formed inward by the l dimension with respect to the ball in the load area, but in practice, the mounting hole should be formed to the extent that it does not come close to the inner peripheral surface of the casing. Therefore, even if the l dimension is increased, there is a limit that the mounting hole cannot be formed inward.

Therefore, in order to shorten the length of the turning path, the sixth
As shown in the figure, looking at the cross section of the casing 2″,
It has been proposed to shorten the length of the direction change path by forming the return hole 7'' above and outward from the ball 10'' in the load area. In this case, if the return hole 7'' is formed 45 degrees outward from the perpendicular line passing through the center of the load ball (the length of the direction change path is shortened),
Although the problem of the aforesaid earlier invention is solved, the arc portion (the arc portion indicated by the dashed-dotted line in the views A and B in FIG. 6) for gradually changing the direction from the raceway groove in an arc shape does not change the direction. Because the length of the road is too short,
As shown in figure b, θ is smaller than 1/4 arc in the direction of view A.
It connects with the arc portion from the return hole on the opposite side at a shorter position, and the raceway surface side and the return hole side cannot be connected tangentially. Therefore, there is a drawback that the ball cannot be moved smoothly in this part.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned drawbacks of the prior art, and is located at a rational position where the smoothest circular arc portion can be formed with respect to the thickness of the side plate of the determined turning path, and the dimensions of the casing can be minimized. It is an object of the present invention to provide a linear motion guide unit with high precision and low sliding resistance by forming a return hole and using a smaller number of balls than required in the prior art.

[Means for solving problems]

The linear motion guide unit of the present invention includes a prismatic rail-like member, a casing having a substantially U-shaped cross section that is slidably mounted on the rail-like member via a large number of balls, and a sliding member of the casing. A side plate is fixed to each end in the moving direction, and a rail-side raceway groove extending in the longitudinal direction is provided on a part of both side faces of the rail-like member, and a rail-side raceway groove is provided on the inner surface of the casing, and the rail-side raceway groove is provided on the inner surface of the casing. casing side raceway grooves are provided in corresponding positions, a load raceway for ball rolling is formed by the two corresponding raceway grooves, a return hole extending parallel to the casing side raceway groove is formed inside the casing; A direction change path is provided inside each of the side plates and connects the raceway groove on the casing side and the return groove, and connects the ball rolling load raceway and the return hole to form a ball rolling endless circulation path. In the linear motion guide unit formed with The return hole is formed so as to pass through the center of the ball in the trackway and be on a straight line parallel to the side surface of the rail-like member having the raceway groove, and the return hole is set at the maximum height of the direction change track formed by the circular arc. The problems in the prior art have been solved by forming the load raceway grooves in the casing at a level, and by making the side surfaces of the rail-like member and the casing in which the load raceway grooves are formed sloped surfaces.

[Effect]

In the linear motion guide unit according to the present invention configured as described above, the larger the inclination angle of the side surface of the rail-shaped member in which the load raceway groove is provided or the inner surface of the casing corresponding thereto, the more The return hole in the casing can be located in the mold in the casing, the mounting hole formed in the casing can be positioned further inward, and the width of the casing, and therefore the width of the entire unit, can be designed to be the minimum. Moreover, it ensures smooth rolling of the ball with little resistance on the direction change path, and also eliminates vibration.
Even under impact, it can perform highly accurate linear motion that can withstand any load in three-dimensional directions.

〔Example〕

The present invention will be explained below based on the accompanying drawings.

FIG. 1 is a projection view showing a specific example of the unit of the present invention. The cross-sectional shape of the rail-like member 1 is generally prismatic, and the cross-section is substantially isosceles trapezoidal, and rail-side raceway grooves 4 are formed in the longitudinal direction of both inclined sides thereof. The casing 2 combined with this rail-like member 1 also has a recessed part formed on its lower surface corresponding to the convex shape of the rail-like member 1, and a casing-side raceway groove 4' is formed on each of its inclined sides. has been done. A loaded raceway for balls rolling is formed between the rail-like member and the casing mounted on the rail-like member by the raceway grooves 4, 4' on the rail side and the casing side, and a large number of balls 10 are placed on this track under load. The casing is slidably held on the rail-like member 1.

During this sliding movement, the ball located within the load raceway advances to the direction change path 5 shown by a broken line in FIG. 7, and the casing slides freely on the rail-like member as a large number of balls roll through the endless circulation path defined by the load track, the return hole 7, and the direction change path 5 that connects the two. move.

FIG. 3 shows an enlarged cross-sectional view of the load trackway portion in one embodiment of the unit of the present invention shown in FIG. The contact point at
One side is formed at a position of 30° and the other at a position of 90° from the horizontal line, making it a highly rigid unit especially against downward loads, but the setting of the angle of the contact point depends on the purpose of use of the unit and This can be done arbitrarily depending on the conditions of use.

In other words, with reference to FIG. 3, each ball inserted between both raceway grooves 4 and 4' contacts each raceway groove at least on the perpendicular line passing through the center of the ball, thereby maximizing the downward load bearing capacity. can do.

FIG. 4 is a sectional view showing the mechanical configuration of the present invention, and this figure shows a specific example of the unit,
In a cross section perpendicular to the axis extending in the sliding direction of the casing 2, a straight line y passing through the center of the ball 9 in the load trackway and parallel to the rail-like member side wall slope 8
An arcuate turning path 5 is formed whose rotation center is an arc having a radius r and having a center on −y. A return hole 7 connected to the direction change path 5
is formed centered on the level of the maximum height (h1) of the arc.

Since the raceway grooves are formed on the inclined surfaces 8, 8', the return hole is positioned further inward of the casing, and the mounting hole 6 provided in the casing 2 can also be formed further inward. The raceway groove of the casing can be easily ground, and the entire unit can be made smaller.

As described above, the present invention secures the minimum necessary length of the direction change path in order to smoothly move the balls in the direction change path, minimizes the number of balls in the no-load area, and reduces the total number of balls in the unit as a whole. It is an object of the present invention to provide a linear motion guide unit whose width can also be minimized.

Although the present invention has been explained based on one specific example of the above unit, the present invention is not limited to the above specific example.

[Effects of the Invention] Since the length of the no-load region portion of the endless circulation path, that is, the direction change path and the return hole can be shortened, the number of balls can be reduced.

The width dimension of the linear motion guide unit can be reduced, and the size can be reduced.

Since the direction change path can be formed as a gentle circular arc path, smooth running of the ball rolling elements can be ensured, and the sliding resistance of the linear motion guide unit can be reduced.

Materials required for the casing, balls, etc. can be saved, and the turning path, raceway grooves, etc. can be easily manufactured at low cost.

Each of the balls in both the load tracks on the casing side and the rail side is in contact with each raceway surface at least on a perpendicular line passing through the center of the ball, so that
The downward load bearing capacity can be maximized.

[Brief explanation of the drawing]

Regarding the drawings, Fig. 1 is a projected view showing the entire unit of the first embodiment of the present invention, Fig. 2 is a front view of a half-cut section of Fig. 1, and Fig. 3 is an enlarged view of the load trackway portion of Fig. 2. 4 is a schematic front view showing the mechanical structure of the unit of the present invention, and FIGS. 5 and 6 are sectional views showing the structure of a linear motion guide unit according to the prior art. 1...Rail-shaped member, 2...Casing, 3...
... Side plate, 4 ... Rail side track groove, 5 ... Turning path, 6 ... Mounting hole, 7 ... Return hole, 8 ... Rail member side wall slope, 8' ... Casing side slope,
9,10...ball. 11... Bottom seal, 12
...Retention band.

Claims (1)

[Scope of Claims] 1. A prismatic rail-like member, a casing having a substantially U-shaped cross section that is slidably mounted on the rail-like member via a number of balls, and a sliding direction of the casing. It consists of a side plate fixed to each end, and a rail-side raceway groove extending in the longitudinal direction is provided on a part of both side surfaces of the rail-like member, and a position corresponding to the rail-side raceway groove is provided on the inner surface of the casing. A raceway groove on the casing side is provided, and a load raceway for ball rolling is formed by the two corresponding raceway grooves, a return hole extending parallel to the casing raceway groove is formed inside the casing, and a return hole is formed inside the casing, and A direction change path is provided inside each of the balls and connects the raceway groove on the casing side and the return groove, and the ball rolling load raceway and the return hole are connected to form a ball rolling endless circulation path. In the linear motion guide unit, (a) the direction change path is formed of a circular arc having a single center in a cross section in the side plate perpendicular to the sliding direction axis of the casing, and the center of the circular arc is (b) the return hole is formed by the circular arc, passing through the center of the ball on the load trackway and being on a straight line parallel to the side surface of the rail-like member having the raceway groove; formed in the casing at the level of the maximum height of the direction change path, (c) the side surfaces of the rail-shaped member and the casing in which the load raceway groove is formed are sloped surfaces, and (d) the rail-side raceway groove and the casing-side raceway A linear motion guide unit characterized in that a ball inserted between both raceway grooves of a groove is in contact with each raceway groove surface at least on a perpendicular line passing through the center of the ball.